Powerhead



Aug. 4, 1964 Filed Aug. 6, 1963 2 Sheets-Sheet 1 36 l i 6/ 25' r l 1/ Hull /3 I g MHnw A; 6

1 lc g \V 'lllt A? L/ IT Hm M INVENTOR PERCY E PRAY %M3/Mri./J

ATTORNEYS United States Patent 3,143,356 POWEREEAE) Percy E. Pray, 3328 Arthur St. NE, Minneapolis 18, Minn. Filed Aug. 6, 1963, Ser. No. 399,244 3 Claims. (Cl. 2794) This invention relates to improvements in powerheads for holding work pieces during machinery operations thereon.

More specifically, this invention is directed to a fluid actuated, piston operated, open-centered powerhead for rapidly closing and opening a collet or arbor on work pieces and having means for simply and easily adjusting the closed diameter of said collet or arbor.

It is an object of this invention to provide a pneu matically operated device for rapidly closing upon and rigidly holding work pieces during machine operations on inside or outside dimensions and then afterwards quickly releasing such work pieces.

It is another object of this invention to provide a device of the class described wherein the closed diameter of the work piece holder is adjusted by rotatably turning a released exposed actuator element for said work piece holder.

It is another object of this invention to provide a powerhead having a fluid actuated, piston operated work piece holder, such holder being so equipped with a releasably locking actuator element that merely rotating the released actuator varies the closed diameter of the work piece holder.

It is another object of this invention to provide a powerhead which is suitable for mounting on any machine table or magnetic surface which can be easily operated manually or which can be synchronized and work with other automated equipment.

It is another object of this invention to provide a powerhead of the class described having a passageway extending completely through the unit thereby adapting the powerhead for bar feeds or for dropping finished parts into a tote pan and for easy tip removal.

Other and further objects will become apparent to those skilled in the art from a reading of the attached specification taken together with the drawings wherein,

FIG. 1 is a top plan view of an embodiment of the powerhead of the invention showing the powerhead mounted on a machine bench, some parts thereof broken away;

FIG. 2 is a side elevational view of the embodiment shown in FIG. 1, some parts thereof broken away;

FIG. 3 is a vertical sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a vertical sectional view, similar to FIG. 3 but showing operation of the powerhead;

FIG. 5 is an enlarged detail sectional view taken along the line 55 of FIG. 1; and

PEG. 6 is an enlarged detail sectional view taken along the line 66 of FIG. 1.

Turning to the drawings, there is seen in FIGS. 1 and 2 an embodiment of a powerhead of the invention herein designated in its entirety by the numeral 10. Powerhead 10 has a generally circular back plate 11. Back plate 11 is equipped with a pair of diametrically oppositely outwardly extending bifurcated ears 12, which adapt the back plate 11 for mounting as by means of a pair of washer-equipped bolts 13 to a mill table 14, as in the embodirnent shown in the drawings. Axially extending in aperture 16 from the bottom face of back plate 11 is a keyway 19. On the top face of back plate 11 and radially spaced from the aperture 16 is formed a shoulder 21.

Rigidly associated with the back plate 11 is a cylinder block 22 whose exterior contours are generally cylindrical and within which is formed a shallow downwardly opening cylinder 23. Cylinder 23 is axially positioned over aperture 16. Cylinder block 22 has a second circular aperture 24 extending through its top wall. Second aperture 24- is axially aligned with the cylinder 23 and hence, is co-axial with aperture 16. As in the case of aperture 16, the second aperture 24 has a groove 26 circumferentially extending in its side wall and groove 26 is adapted to receive an O-ring seal 27. In cylinder block 22, an annular shoulder 28 is formed which downwardly extends in cylinder 23 from the top wall of the block 22 adjacent the side walls of cylinder 23 in the manner shown, for example, in FIGS. 4 and 3.

To rigidly associate cylinder block 22 with the back plate 11, the back plate 11 has formed in it on a suitable bolt circle, six equally spaced counter sunk holes and in the cylinder block 22 are formed six meeting holes transversely extending into the side walls thereof, each of the latter holes being fitted. Then, when the cylinder block 22 is mounted on the back plate 11 with a sealing gasket 25 therebetween, the cylinder block 22 is secured to the back plate 11 by means of Allen head cap screws 29. Those skilled in the art will appreciate, however, that any conventional means can be employed to mount the cylinder block 22 against the back plate 11.

Extending through the side wall of cylinder block 22 to communicate with cylinder 23 are a pair of fluid passages 31 and 32, each of which is threaded with a conventional fitting 33 (paired). Fluid passages 31 communicate with the bottom portion of cylinder 23, and fluid passage 32 communicates with the top portion of cylinder 23.

A cylindrical drawbar 34 extends axially through the axial aperture 16 and 24, respectively, for axial sliding movements relative to the cylinder block 22 and back plate 11. Observe that, taken together, the cylinder block 22 and back plate 11 co-act together and can be considered to form a casing structure. Observe that the lower end of drawbar 34 is diametrically slotted for receipt of a key 36. Key 36 is adapted to meet with the keyway 19 whereby rotary movements of the drawbar 34 relative to the cylinder block 22 and back plate 11 is substantially prevented. In the embodiment shown, the upper portion of drawbar 34 has slightly larger inside and outside dimensions than the corresponding bottom portions of the same drawbar 34. The inside walls of the top portion of drawbar 34 are threaded. Circumferentially extending around the outside wall of drawbar 34 in a region between the upper and lower portions thereof is a shoulder 37.

Mounted on drawbar 34 concentrically for common amal movements therewith is a piston 38. The piston 38 is positioned within the cylinder 23 for axial reciprocatory sliding movements responsive to fluid pressure alternatively applied to the respective top and bottom faces of the piston 38 in the top and bottom portions, respectively, of the cylinder 23. Circumferentially formed in the side wall of piston 33 is a groove 39 which is adapted to receive an O-ring seal 41. Observe that the O-ring seal slidably engages the cylindrical wall of cylinder 23. In the embodiment shown, the drawbar 34 axially extends through the piston 38, there being an appropriately formed aperture 43 through the piston 38 transversely extending. The lower portion of the drawbar 34 is adapted to extend through this aperture 43 in the piston 38, and the top face of the piston 38 is slid upward along the drawbar 34 until the shoulder 37 contacts the face of the piston 38 adjacent this aperture 43. Then, circumferentially extending in the lower portion of drawbar 34 immediately below piston 38 is a suitably formed groove which is adapted to receive a retaining ring 42 with the result that the piston 38 is thereby joined to the drawbar 34 for common and axial reciprocatory sliding movements relative to the cylinder block 22 and back plate 11. In order to provide a sealing engagement between the drawbar 34 and the piston 38, there is provided on the side wall of aperture 43 of piston 38 a groove 44 which is adapted to receive an O-ring seal 46, the 'O-ring seal 46 making a fluid-tight seal between the piston 38 and the drawbar 34.

Observe that when a fluid such as air under pressure is introduced into the passage 31, the piston 38 is forced upward; and when the pressure of fluid such as air is forced through the passage 32, the piston 38 is forced downward. Upward movement of the piston 38 is limited by the shoulder 28, while downward movement of the piston 38 is limited by shoulder 21, within the cylinder 23.

From the upper portion of the drawbar 34 axially outwardly extends a generally cylindrical Work piece holder, here a collet 47, the numeral 47 designating the entire collet. In place of collet 47 there can be employed an arbor, as those skilled in the art will appreciate, as the work piece holder. No arbor is shown in the attached drawings. As is the case with work piece holders, generally, the collet 47 here is longitudinally split at its outer end portion to provide a plurality of radially inwardly and outwardly movable gripping elements or fingers 48. Fingers 48 are yieldingly biased in one direction of radial movement thereof. Here, upon the exterior surfaces of the collet fingers 48, the fingers 48 are joined to one another in the base region 49 of the collet 47. The base region 49 is threaded on its outside walls and adapted to engage the threads in the upper portion of the drawbar 34, as described. The collet 47 is adjustably secured at its inner end to the drawbar 34 for common axial movements therewith and at the same time to provide means for moving the collet fingers 48 longitudinally axially of the drawbar 34.

In FIGS. 3 and 4 the operation of the powerhead is demonstrated with the use of a length of bar stock 50 as the work piece. With the collet fingers 48 in their open or relaxed position, as shown in FIG. 3, the bar stock 50' is inserted therebetween. Then, when the piston 38 is moved downwardly by fluid pressure applied to the upper face thereof, as described, the collet fingers 48 are cammed against the conical surfaces at the inner upper end of actuator element 51. When the collet fingers 48 are cammed by the tapered upper end portion 52 of actuator element 51, the diameter of the work piece holder is effectively diminished so that when the piston 38 has been moved to its lowermost position, as shown for example in FIG. 4, the collet fingers 48 have been moved to their position of closure. Thus, in FIGS. 3 and 4 the position of closure represents a closed diameter for the collet fingers 48 slightly less than the diameter of the bar stock 56. Thus, the bar stock 50 is securely held by the collet fingers 48 when the collet 47 has been closed thereupon thereby producing bias of the collet fingers 48 against the'bar stock 50 by the tapered upper end portion 52 of actuator element 51.

To control radial movements of the gripping elements or fingers 48, there is provided an actuator element 51. The actuator element 51 is generally cylindrical and consists of a tapered upper end portion 52 and a lower base portion 53, in the embodiment shown. The actuator element 51 generally circumscribes the collet 47. The tapered upper end portion 52 has a taper on its inside walls which outwardly diverges toward the upper end of actuator element 51. If tapered upper end portion 52 is adapted to engage the tips of the fingers 48 of collet 47 and to cam these fingers radially inwardly against their yielding bias responsive to axial movements of the piston and drawbar in a downward direction.

The base portion 53 and actuator element 51 are flanged outwardly and circumferentially. The base portion 53 is adapted to rest upon the top portion of the cylindrical block 22. In order to impart adjusting movement to the work piece holder (here, collet 47) relative to the drawbar 34, there is provided independent means operatively connecting the actuator element 51 to the work piece holder (collet 47 In the embodiment shown, such independent means for operatively so connecting actuator element 51 to collet 47 is provided by means of a key 54 which fits into appropriately formed keyways 56 and 57 in collet 47 and actuator element 51, respectively.

In order to fix the position of the Work piece holder to the drawbar 34, it is necessary to provide means for releasably locking the actuator element 51 against movements in directions which would effect axial movement of the work piece holder relative to the drawbar 34. Thus, in the embodiment shown, a thrust plate 58 is provided which is an elliptically shaped member having a centrally located transversely extending aperture 59 therethrough. The bottom face of thrust plate 58 is adapted to fit against the upper face of the cylinder block 22 and retain sectionally the base portion 53 of actuator 1 element 51. For this purpose, the thrust plate 58 is provided with a circumferentially extending upwardly projecting shoulder 61 adjacent the aperture 59 and the bottom or lower face of the thrust plate 58 adjacent the aperture 5 3 is grooved 62 for receipt of the flanged portions of the base 53 of actuator element 51.

Along the long axis of the thrust plate 58 near its opposed outer end portions are positioned a pair of transversely extending holes which are countersunk and adapted to receive Allen head cap screws. Meeting with these holes, a similar pair of holes which are threaded are formed in the top of cylinder block 22, thereby enabling the thrust plate 58 to be demountably mounted against the cylinder block 22. Those skilled in the art will appreciate that in place of the thrust plate 58, any means can be used to releasably lock the actuator element 51 against movements in directions to adjust the work piece holder (here, collet 47) so as to vary the closed diameter of the work piece holder by the term closed diameter, reference is had to the distance across the work piece holder (here, collet 47 in the region of the suitable gripping elements or fingers 48.

Optionally, as a matter of convenience or esthetics, the exposed surfaces of the actuator element 51 can be knurled, as shown at 63 in FIG. 2, so as to provide a better surface for manually gripping the outside walls of the actuator element 51 during adjusting movements; i.e., rotating the actuator element 51 when the collet 47 is axially extended or retracted relative to the drawbar 34.

The mill table 14 is of the conventional type and does not constitute a part of this invention and hence, is not described in detail herein.

It will be observed that in the embodiment shown, a passageway extends axially completely through the powerhead 10 thereby adapting the unit for bar feeds, for dropping finished parts into a tote pan or the like, and permitting easy tip removal from the collet fingers 48.

It will be appreciated that the powerhead 10 can be used as an air operated device employing automatic, semi-automatic, or manual valving.

.So long as fluid is maintained in the upper portion of the cylinder 23, the powerhead rigidly holds parts for machine operation but that as soon as the cylinder is removed in a reverse direction as through application of air pressure to the reverse means of the piston, there is achieved an immediate release of the part thereby permitting the insertion of a new part for a repeat or separate machine operation. The construction of the back plate 11 permits the powerhead to be mounted on any machine table or magnetic surface.

This invention has been thoroughly tested and found to be completely satisfactory for the accomplishment of the above objects; and while I have shown and described above a preferred embodiment thereof in which the principles of the present invention have been incorporated, I wish it to be specifically understood that the same may be modified without departure from the scope and spirit of the appended claims.

What I claim is:

1. A powerhead for holding work pieces comprising:

(a) a casing adapted to be secured to the Work supporting portion of a machine tool and defining a cylindrical chamber, a pair of fluid passages one each communicating with an opposite end of said chamber, and axial openings through each opposite end thereof to said chamber,

(b) a cylindrical drawbar extending axially through said axial openings for axial sliding movements relative to said casing and keyed to said casing against rotary movements relative thereto,

(c) a piston concentrically mounted on said drawbar for common axial movements therewith within said chamber and having a sealing ring slidably engaging the cylindrical wall of said chamber,

(d) said piston and drawbar being moved alternately in opposite directions axially of said chamber responsive to introduction of fluid under pressure alternately to opposite ends of said cylinder through said passages,

(e) a generally cylindrical work piece holder extending axially outwardly from one end of said drawbar and axially adjustably secured at its inner end to said drawbar for common axial movements therewith and for adjustable movements axially of said drawbar,

(1) said holder being longitudinally split at its outer end portion outwardly of said casing to provide a plurality of radially inwardly and outwardly movable gripping elements yieldingly biased in one direction of radial movement thereof,

(g) an actuator element mounted on said casing and engaging said movable gripping elements to impart movements thereto in a direction against said yielding bias responsive to axial movement of said piston and drawbar in one direction,

(h) independent means operatively connecting said actuator element to said work piece holder for im parting adjusting movement to said holder relative to said drawbar, and

(1') means for releasably locking said actuator element against movements in directions to adjust said Work piece holder.

2. A powerhead for holding Work pieces comprising:

(a) a casing adapted to be secured to the work supporting portion of a machine tool and defining a cylindrical chamber, a pair of fluid passages one each communicating with an opposite end of said chamher, and a pair of circular coaxial openings, one through each opposite end thereof through said chamber,

(17) a cylindrical drawbar extending axially through said coaxial opening for axial sliding movements relative to said casing and having a head end protruding from said casing,

(c) first keying means functionally associating said drawbar with said casing against rotary movements of said drawbar relative to said casing,

(d) a piston concentrically mounted on said drawbar for common axial movements therewith within said chamber and having a sealing ring slidably engaging the cylindrical wall of said chamber,

(e) said piston and said drawbar being moved alternately in opposite directions axially of said chamber responsive to introduction of fluid under pressure alternately to opposite ends of said cylinder through said passages,

(f) a generally cylindrical work piece holder extending axially outwardly from one end of said drawbar and axially adjustably secured at its inner end for common axial movements therewith and for adjustable movements axially of said drawbar,

(g) said holder being longitudinally split at its outer end portion outwardly of said casing to provide a plurality of radially inwardly and outwardly movable gripping elements yieldingly biased in one direction of radial movement thereof,

(h) a cylindrical actuator element mounted on said casing and positioned circumferentially about said holder,

(i) said actuator element engaging said movable gripping elements to impart movements thereto in a di rection against said yielding bias responsive to axial movements of said piston and said drawbar in one direction,

(j) second keying means functionally associating said holder and said actuator element for common adjust able movements axially of said drawbar, and

(k) a thrust plate releasably mounted on said casing about said actuator element and adapted to lock said actuator element against movements in directions to adjust said work piece holder.

3. A powerhead for holding work pieces comprising:

(a) a casing adapted to be secured to the work supporting portion of a machine tool and defining a cylindrical chamber, a pair of fluid passages one each communicating with an opposite end of said chamher, and a pair of circular coaxial openings, one through each opposite end thereof through said chamber,

(b) a cylindr cal drawbar extending axially through said coaxial opening for axial sliding movements relative to said casing and having a head end protruding from said casing,

(c) first keying means functionally associating said drawbar with said casing against rotary movements of said drawbar relative to said casing,

(d) a piston concentrically mounted on said drawbar for common axial movements therewith within said chamber and having a sealing ring slidably engaging the cylindrical wall of said chamber,

(e) said piston and said drawbar being moved alternately in opposite directions axially of said chamber responsive to introduction of fluid under pressure alternately to opposite ends of said cylinder through said passages,

(f) a collet, including a base and a plurality of upwardly extending, radially inwardly and outwardly movable fingers, yieldingly biased for radial outward movements,

(g) said collet having its base threadably engaged with said head end of said drawbar for adjustable move ments axially of said drawbar and for common axial movements with said drawbar,

(h) an actuator element mounted on said casing and circumferentially positioned about said collet,

(i) said actuator element being adapted to engage said movable gripping elements to impart movements thereto in a direction against said yielding bias responsive to axial movement of said piston and said drawbar in one direction,

(1') second keying means functionally associating said holder and said actuator element for common adjustable movements axially of said drawbar, and

(k) a thrust plate releasably mounted on said casing about said actuator element and adapted to lock said actuator element against movements in directions to adjust said work piece holder.

References Cited in the file of this patent UNITED STATES PATENTS 2,418,082. Marasko Mar. 25, 1947 2,689,739 May Sept 21, 1954 3,030,119 Myers Apr. 17, 1962 3,087,736 Lukas Apr. 30, 1963 

1. A POWERHEAD FOR HOLDING WORK PIECE COMPRISING; (A) A CASING ADAPTED TO BE SECURED TO THE WORK SUPPORTING PORTION OF A MACHINE TOOL AND DEFINING A CYLINDRICAL CHAMBER, A PAIR OF FLUID PASSAGE ONE EACH COMMUNICATING WITH AN OPPOSITE END OF SAID CHAMBER, AND AXIAL OPENINGS THROUGH EACH OPPOSITE END THEREOF TO SAID CHAMBER. (B) A CYLINDRICAL DRAWBAR EXTENDING AXIALLY THROUGH SAID AXIAL OPENINGS FOR AXIAL SLIDING MOVEMENTS RELATIVE TO SAID CASING AND KEYED TO SAID CASING AGAINST ROTARY MOVEMENT RELATIVE THERETO, (C) A PISTON CONCENTRICALLY MOUNTED ON SAID DRAWBAR FOR COMMON AXIAL MOVEMENTS THEREWITH WITHIN SAID CHAMBER AND HAVING A SEALING RING SLIDABLY ENGAGING THE CYLINDRICAL WALL OF SAID CHAMBER, (D) SAID PISTON AND DRAWBAR BEING MOVED ALTERNATELY IN OPPOSITE DIRECTIONS AXIALLY OF SAID CHAMBER RESPONSIVE TO INTRODUCTION OF FLUID UNDER PRESSURE ALTERNATELY TO OPPOSITE ENDS OF SAID CYLINDER THROUGH SAID PASSAGES, (E) A GENERALLY CYLINDRICAL WORK PIECE HOLDER EXTENDING AXIALLY OUTWARDLY FROM ONE END OF SAID DRAWBAR AND AXIALLY ADJUSTABLY SECURED AT ITS INNER END TO SAID DRAWBAR FOR COMMON AXIAL MOVEMENTS THEREWITH AND FOR ADJUSTABLE MOVEMENTS AXIALLY OF SAID DRAWBAR, (F) SAID HOLDER BEING LONGITUDINALLY SPLIT AT ITS OUTER END PORTION OUTWARDLY OF SAID CASING TO PROVIDE A PLURALITY OF RADIALLY INWARDLY AND OUTWARDLY MOVABLE GRIPPING ELEMENTS YIELDINGLY BIASED IN ONE DIRECTION OF RADIAL MOVEMENT THEREOF, (G) AN ACTUATOR ELEMENT MOUNTED ON SAID CASING AND ENGAGING SAID MOVABLE GRIPPING ELEMENTS TO IMPART MOVEMENTS THERETO IN A DIRECTION AGAINST SAID YIELDING BIAS RESPONSIVE TO AXIAL MOVEMENT OF SAID PISTON AND DRAWBAR IN ONE DIRECTION, (H) INDEPENDENT MEANS OPERATIVELY CONNECTING SAID ACTUATOR ELEMENT TO SAID WORK PIECE HOLDER FOR IMPARTING ADJUSTING MOVEMENT TO SAID HOLDER RELATIVE TO SAID DRAWBAR, AND (I) MEANS FOR RELEASABLY LOCKING SAID ACTUATOR ELEMENT AGAINST MOVEMENTS IN DIRECTIONS TO ADJUST SAID WORK PIECE HOLDER. 